Triple ring to double ring?

scorpionryder said:

Hi,
I'm thinking about changing my Cannonadale badboy Hybrid commuter bike over from a 3 ring MTB (42,34,22 IIRC ) set to a 2 ring road bike set. I ride everyday about 25 miles roundtrip with about 6-8 miles of that a fairly steep climb.

I currently have a worn Truvative FireX and wish to upgrade.

Can anyone recommend a decent road crankset around $200?
I was initialy looking at the shimano 105, mostly for the price with a standard rear road cassette.

Will I give up any noticeable climbing ability with straight road gearing?

thanks

Go to, analyticcycling.com and click on: Gears, Speed, Cadence and you can calculate what combination of double ring and cassette comes closest to giving you the ratios you have now, that you want to retain. Then you can select the supplier. A Compact 34-50, with a 12-25 cassette will give you a very low gear and a 40+ mph top gear, without too high a cadence. But only YOU can determine what ratios will work best.

How many speed is the bike, 8 or 9? You will have to consider shifters and derailleurs if you go to 9 speed road components and a 16 tooth shift on the front. 😉

gclark8 said:

How many speed is the bike, 8 or 9? You will have to consider shifters and derailleurs if you go to 9 speed road components and a 16 tooth shift on the front. 😉

It's a 9 spd cassette.
The mtb and road components are not compatible?
If I have to switch everything, I'll just replace what I have for same.

I would like to get a road bike high speed gear though.

The first thing to do is to figure out what gear ratios you actually use now. If you are using your lowest possible gear for example, a road crankset simply isn't going to work for you.

Once you do that, you need to figure out the gear ratios that are possible with any of the crankset combinations you are considering. That will help you to decide what you want.

Once you know for sure what you want, the next step is to figure out if it will work. Check out where your chainrings pass your chainstay. Now imagine a chainring with a bigger diameter. Are you going to have enough clearance? You'll probably need a road front derailleur to match the arc of the bigger chainring but that shouldn't be a problem because it looks to me like you have down tube cable routing. In spite of what Shimano says, mountain shifters had been successfully paired with road front derailleurs for many years before Shimano finally produced a flat bar road shifter set.

OK, 9 speed, Just replace the crankset with a MTB (Deore/Sugino) 28/38/48 triple. The 9 speed cassette will already have an 11 tooth top gear. This will give the best result with minimum fuss. I have done this Crankset conversion to several MTBs.

For gear calcs, before and after, plug it all into http://sheldonbrown.com/gears/

gclark8 said:

The 9 speed cassette will already have an 11 tooth top gear.

You sure? my 9 speed cassette is 12-23

mrkott3r said:

You sure? my 9 speed cassette is 12-23

Yours is a road cassette, his is a 9 speed Mega range, 11-32 or 11-34. Look at the pix. :eek:

Yes, 11-34 cassette

I am leaning toward the 105, 53x39.

[IMG]nashbar.comSH FC5502.gifOpen ↗[/IMG]

reckon I'll get the same rear cog and a front derailer and should be fine. no?

scorpionryder said:

Yes, 11-34 cassette

I am leaning toward the 105, 53x39.

reckon I'll get the same rear cog and a front derailer and should be fine. no?

That 105 crank should work, nicely ...

BUT, here's what you need to know (see the attached picture of my still-incomplete, spare-parts/project bike as of about a week ago) ...

Unfortunately, the BB you have has a different spindle than the ROAD Octalink (the XT & LX Octalink is a hair smaller ... you can MOUNT the ROAD crank on it, but it probably would damage the ROAD crank's mating notches).

You'll PROBABLY need a 118mm bottom bracket which is intended for a triple BECAUSE of the rear stays ... that's not necessarily a bad thing if you can get a 105 triple for only a modest-or-no additional cost (and, simply remove & stash the granny away for if/when you ever decide you need it!) ... otherwise, just get the double.

The crank on the bike in the picture has a 118mm ISIS spindle instead of a 113mm to ensure the crank arms would clear the rear stays -- I have made the same "observation" on an aluminum touring frame that I had which ALSO needed a 118mm Octalink to get the 52t chainring to clear the stays. The particular crank is in the picture is an FSA Gossamer with 52/39 chainrings ...

You can keep using the same front derailleur despite what some people may say because the outer cage of the "low" profile MTB front derailleur is actually the same as the outer cage profile of a standard ROAD front derailleur designed for a double crank. The front derailleur is an XT ("top" pull).

The picture shows an 12-30 (custom re-stacked 9-speed which started as a 12-27 Ultegra onto which a 30t was mated), but the short cage 105 was actually capable of handling a 32t, but not a 34t, large cog. You can continue to use your current cassette & rear derailleur, of course!

FWIW. The frame, if you couldn't tell, is actually an "extra" hardtail frame that I had to which I mated a road fork. The center of the BB is 11" above the ground with the ROAD fork & minimalist road tires ... the BB would be higher with a CX fork. The particular brakes calipers are Tektro long reach which work because the "brake" bridge on the seat stays is a suitable distance AND the particular fork has (I think) clearance for a 700x28 tire.

scorpionryder said:

Yes, 11-34 cassette

I am leaning toward the 105, 53x39.

reckon I'll get the same rear cog and a front derailer and should be fine. no?

If you're using MTB shifters, you won't be able to use a road crankset - cable pull is slightly different between the two, and although you may be able to get it to shift with a lot of work, it will be VERY fiddly and unreliable.

I would suggest going with George's solution (48T MTB crankset) - saves you having to swap to road flatbar shifters.

nerdag said:

If you're using MTB shifters, you won't be able to use a road crankset - cable pull is slightly different between the two, and although you may be able to get it to shift with a lot of work, it will be VERY fiddly and unreliable.

This isn't quite correct ...

The chainring spacing is the same on ROAD & MTB cranks ... you obviously have shifters & a front derailleur which will be compatible with one another. As noted, the outer cage of the MTB front derailleur is fine with a ROAD crank (hence the earlier, attached picture -- you know, a picture is worth a thousand words).

If your bike has an ISIS BB (which it probably does ... and, it probably has an appropriately-long 118mm spindle), then you could get an FSA Gossamer ROAD crank like the one on my "project" bike -- the FSA ROAD crank has the same 130BCD as Shimano ROAD cranks (if that matters to you). The FSA Gossamer cranks are very much a bargain ... should be well under $100US because it lacks sex-appeal for most people.

The 105 9-speed shifter on my project bike happens to require 1.5 shifts (3 clicks) to move the particular XT front derailleur ... it was actually a bottom pull front derailleur which I "modified" slightly to use as a top pull. This is something I knew could get away with since I originally had set up the bike with Campagnolo ERGO shifters ... still, no problems, per se, when using the 105 shifters + XT front derailleur with a double -- YOUR results may vary, of course ... but, the only thing you should need to do is to loosen the front derailleur's clamp and reposition the front derailleur a little higher on the seatpost so that it will accommodate whatever your new chainring size; and, of course, you will have to retension the front derailleur cable.

FWIW. If you ever choose to go with ROAD bars + ROAD shifters, then I strongly recommend Campagnolo ERGO shifters -- I actually had Campagnolo shifters set up on the bike, initially (see attachment of earlier rendering ... I may end up going back to ERGO shifters), but as I noted, the bike is a spare-parts bike, and the 105 shifters are something I had lying around looking for a "home" ...

... Everything shifts fine on-the-stand AND when set up in a stationary trainer ... AND, that is with unforgiving, 8-speed, unpinned & unramped chainrings mounted in the crank! The only time the shifting is hesitant, so far, is when I have been hesitant (it has been a while since I used STI shifters with their L-O-N-G shifting motion).

nerdag said:

I would suggest going with George's solution (48T MTB crankset) - saves you having to swap to road flatbar shifters.

BTW. You can just buy new chainings for your TruVativ crank. As noted, Shimano has a 48t 104BCD "touring" chainring.

MTB gearing, 48-11 (4.46)
is faster and cheaper than
Road Gearing, 52-12. (4.33) 😄

gclark8 said:

MTB gearing, 48-11 (4.46)
is faster and cheaper than
Road Gearing, 52-12. (4.33) 😄

Interesting. . .

Wouldn't the simple solution be just stick with the MTB triple and get a 52 chainring up front?

I really just wanted a higher gear to keep up with traffic.
If that's the case then maybe Truvative stylo.

scorpionryder said:

Interesting. . .

Wouldn't the simple solution be just stick with the MTB triple and get a 52 chainring up front?

I really just wanted a higher gear to keep up with traffic.
If that's the case then maybe Truvative stylo.

Well, THAT isn't how you originally started the thread!

Regardless, AFAIK, no one makes a 52t OR even a 50t 104BCD chainring; but, maybe there is a 104BCD downhill ring with that tooth count.

The "old" XTR 112BCD DH rings come in sizes between 46t & 54t.

There is little advantage to changing from the one TruVativ crank to another, IMO ... you can just get that 48t 104BCD SHIMANO chainring + a new 32t inner/middle chainring for your existing crank as a starter ...

Thanks!
I think I've got my head around this.

I'll shop for a 48t Shimano chainring with a 4 bolt pattern

I keep my scratched up truVativ spindle for now.

While I can see why someone would want to replace some of their chainrings with bigger ones, I don't understand why someone would want to go to 2 chainrings instead of 3. I think the granny gear is very useful. Those long, tough ascents really could use a granny gear. Ever bike in New Hampshire or any hilly area for that matter? I think replacing the chainrings with bigger ones would make more sense, and also would make it possible not to have to replace both a derailleur and a shifter. Just an opinion from a road cyclist who likes his granny gear but wishes he had some higher speed gears also! 🙂

I think this may be the ticket

46t x 104mm - 4 bolt - Black Alloy

or this:

104 x 48t Black Alloy

Go the 48t. 😄